How to Change the Battery in a Mercedes Key


1. Turn your Smart Key over, and push down the backup key locking tab.
2. Slide the backup key away from the edge of the Smart Key. Insert the backup key into its storage compartment; slide the key toward the locking tab to unlatch the battery storage compartment.
3. Pull the battery storage compartment out when it pops up. Remove the batteries from the compartment.
4. Insert the new batteries. Line up the positive side (+) with the contact clamp (face up). Reinsert the battery storage compartment into the Smart Key.
5. Replace the backup. Slide the backup key's arm into its mount; push it down to secure it.